Variable reactor



J. KERRIGAN VARIABLE REACTOR Filed Nov. 13, 1929 INVENTOR Jo/m (err/yam.

' ATTORNEY Patented Aug. 16, 1932 UNITED STATES PATENT OFFICE JOHN KEBRIGAN, 01' BPml'mD, IABSACH USETTS, ASSIGNOR TO WESTINGHOUSE ELECTRIC & KANUFAGTUBIIIG OOIPANY, A CORPORATION OF PENNSYLVANIA VARIABLE REACTOR Application fled Iovember 18, 1929. Serial No. 406,901.

My invention relates to variable reactors and it has particular relation to variable condensers of the types commonly used for tuning purposes in radio-receiving apparatus.

Considerable difliculty has been experienced by receiving-set manufacturers in so pre-adj usting the various components of their sets, particu arly those of the type comprising a plurality of condensers simultaneously actuated by a single control-device, that a plurality of tuned circuits may be maintained in syntony throughout the'tuning range.

The difficulty arises, mainly, through the inability of manufacturers to-so build a plurality of condenser-units that, when the said units are actuated in unison, each will have the same capacity at any given dial-setting.

it has, accordingly, been previously proposed to provide radial slots in the end rotorplates of each condenser in a gang and to bend the sectors inwardly or outwardly to correct the capacity-displacement curve. It has also been proposed to provide an auxiliary trimming, or vernier condenser for each of themain condensers and to actuate the verniers by cams that are individual to the said main condensers.

The slotted-end-plate condensers, however, do not well retain their adjustment when the receiving sets are subjected to rough handling during shipment thereof, and the camactuated Vernier devices are relatively expensive.

It is, accordingly, an object of my invention to rovide a variable condenser, the capacity- 'splacement curve of which may be modified after the device has been incorporated into a radio-receiver.

Another object of my invention is to provide a device, of the t described, that shall be capable of retaining its adjustment even though hand-led roughly during shipment.

Another object of my invention is to provide a pre-adjustable variable condenser that shall be relatively inexpensive to.manufacture.

Still another, and more specific, ob'ect of my invention is. to provide a variab econdenser, the capacity-displacement curve of Accordin to my invention, I provide the 'rotor-assem ly of a variable condenser with a plurality of auxiliary, angularly adjustable, blades, and provide one of the endplates ofthe stator-assembly with a small, elongated plate that extends inwardly from the periphery of the plate to beneath the paths swept by the auxiliary plates when the rotor-assembly is turned upon its shaft.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of certain specific embodiments, when read-in connection with the accompanying drawing, in which:

Figure 1 is view, in perspective, ofva variable condenser comprising a preferred embodiment (if my invention, a portion of the framework being broken away;

Fig. 2 is a fragmentary view of the device shown in Fig. 1, as seen from above;

Fig. 3 is an end view, in elevation, of the device,'to which reference will, hereinafter, be made in describing the operation of adjusting a radio-receiver comprising variable condensers constructed according to my invention;

Fig. 4 is an enlarged detail view, partly in section, of the auxiliary-blade assembly.

The condenser illustrated in F ig. 1 comprises a plurality of end-plates 1, referably metallic, between which extend a urality of bars 2 of insulating material. X stator-assembly, comprising a plurality of plates 3, is supported from the insulating bars. The stator-plates are electrically connected to each other by any suitable means, such as metallic spacers (not shown). y

A shaft 4 is rotatably mounted in the endplates 1 and carries a plurality of rotorlates 5. The shaft also carries a plurality o auxiliary plates 6,7, and 8.

The auxiliary plates are rotatably mounted upon a hub lO that is slidably and rotatably supported upon the shaft 4. One end of the hub'has a shoulder 11 that is spun, or otherwise formed, after the auxiliary plates have been mounted thereon. The opposite end of the hub ,is provided with a flan e 12, and a spring-washer 13, is interpose between the fiange and the auxiliary blade nearest thereto. A set screw 14 extends through the flange 12 to hold the blade-assembly in adjusted position on the shaft.

A small, elongated plate 15 is afiixed to the outer side of the stator plate nearest to the auxiliary rotor-plates and extends inwardly to beneath the paths swept by the said auxiliary plates when the shaft is turned.

The operation of lining-up a radio receiver, comprising a plurality of my improved condensersinterconnected for simultaneous actuation, as by a common shaft, is facilitated if each rotor-assembly is marked ofi into as many zones as there are auxiliar plates, as illustrated by the zones A, B and (l in Fig. 3.

The condenser-rotors are first displaced from the all-out or minimum capacity position, until the plates of zones A are entirely interleaved with the stator plates. In this position, the auxiliary plates 6, which should now overlie the elongated plates 15, in each condenser, are moved angularly or bent inwardly or outwardly, until the capacities of the condensers are equalized, and the circuits tuned thereby are in syntony.

The rotors are next displaced further, until the plates of both zone A and zone B are interleaved with the stator plates, and the capacities are equalized by adjustment of the auxiliary plates 7 with respect to the elongated plates 15. The same performance is repeated for complete interleaving of the condenser plates, or the maximum-capacity position, the auxiliary plates 8 being the last ones to be bent or angularly moved.

Naturally, as many auxiliary plates may be supplied with each condenser, as may be necessary to obtain a'sufiiciently smooth capacity-displac'ement curve for commercial radio-receivers but, in most instances five or six plates per condenser have been :tound to be enough.

My improved variable condenser is mainly advantageous in that the adjustment thereof, after having once been fixed at the factory is not liable to change during shipment of the device or during subsequent'use by the purchaser. In this respect, it is superior to condensers having slotted end plates, since the capacity of the latter is prone to change when the devices are jarred and with changes in temperature. 7

Furthermore, no special tools are required for adjusting the capacity, an ordinary small screw-driver, being the only implement required.

Although I have shown and described a specific embodiment of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necemitated by the prior art or by the spirit of the appended claims.

I claim asmy invention:

1. A variable condenser comprising a fixed elementand a movable element so disposed with respect to each other as to be capable of having a continuous capacity-displacement characteristic, auxiliary elements movable in unison with said movable element, and a relatively small-fixed element cooperating with said auxiliary elements in their movement to give discontinuous increments of capacity to said condenser at predetermined positions.

2. In a variable condenser, a plurality of rotor-plates aflixed to a shaft, a plurality of angularly adjustable auxiliary rotor-plates rotatably mounted on said shaft, said auxiliary plates being made of a bendable material, means for maintaining said auxiliary plates in adjusted position, and a small stator- I plate, electrically connected to the stator of said variable condenser so disposed as to suecessively cooperate with said rotor plates to give discontinuous increments of capacity to said condenser at predetermined positions, whereby the capacity-displacement characteristic of said condenser may be matched with the characteristic of a-similar condenser.

In testimony whereof, I have hereunto subscribed my name this 8th day of Nov. 1929.

JOHN KERRIGAN. 

